The aim of this SBIR proposal is to develop a novel, rapid, homogeneous assay for high throughput screening which is capable of detecting affinity interactions between antibody/antigen, receptor/ligand, and enzyme/substrate. High throughput screening (HTS) assays based on this new technology will have applications in pharmaceutical and biotechnology combinatorial drug discovery programs. The specific aims will be to develop novel reagents used in the assay, optimize assay conditions and develop instrumentation for performing the assay. The HTS assay combines the use of specially formulated photosynthetic membrane and fluorescence detection. The proposed work will focus on developing an HTS assay for identification of inhibitors of protein tyrosine kinases involved in signal transduction. An assay will be developed to identify inhibitors of src, an oncogenic protein tyrosine kinase overexpressed in certain cancer cells. PROPOSED COMMERCIAL APPLICATION: The high throughput screening assay has commercial applications in drug discovery programs and will be marketed to pharmaceutical and biotechnology companies. The technology can also be developed for application in vitro diagnostic assays for use in the biomedical, food, dairy and environmental industries.